What circumstantial evidence?
https://www.wsj.com/articles/the-world-needs-a-real-investig...
There's also been a string of academic preprints and articles, like
https://arxiv.org/ftp/arxiv/papers/2102/2102.03910.pdf
The authors tend to be kind of fringe, not surprisingly given the reputational cost (and given that if a lab origin is ever confirmed, many of the techniques that top researchers have spent their lives mastering will probably become illegal). A lot of very senior virologists are on the record as open to the possibility of a lab escape, though, for example:
> Baric said he still thought the virus came from bats in southern China, perhaps directly, or possibly via an intermediate host, although the smuggled pangolins, in his view, were a red herring. The disease evolved in humans over time without being noticed, he suspected, becoming gradually more infectious, and eventually a person carried it to Wuhan “and the pandemic took off.” Then he said, “Can you rule out a laboratory escape? The answer in this case is probably not.”
https://nymag.com/intelligencer/article/coronavirus-lab-esca...
I don't recommend that article in general; the author uses his talents as a novelist to paint a more vivid picture than I believe the evidence justifies. I do trust him to faithfully print the quote, though.
And as your first article details, the "lab accident" theory rests on some lab doing secret virus experiments. Even if you find a whole sea of the virus in some cave, someone will argue they could have gotten there after the first "accident". Good luck disproving that without letting US virologists snoop in every lab in China.
To me "open to the possibility" is a very strong reading of "can't rule it out".